With the development of network communication technology, applications of making video communication between communication terminals are more and more common.
In traditional video communication, when size of a video window in a local receiver is changed (e.g., scaled by a user), the receiver, according to the video quality statistics in a certain time, informs the video source encoder on the sender side to modify the encoding rate, resolution, bit rate, frame rate and other parameters via real time transport protocol (RTCP), to eventually adapt to the changes of the video window size. Therefore, even if the video window size of the receiver is changed, the video source encoder on the sender side remains in the same encoding strategy for a certain time.
The traditional video communication technology notifies the encoder on the sender side to make change completely basing on the statistical results of recent video quality. A certain response time is required for the sender to fully adapt the scaling operation of video window size on the receiver side. Therefore, the efficiency is low. Especially, when a large window is scaled to a small window, a long response time and a wide bandwidth is needed, which thereby impacts the ability of other video channels to effectively use the bandwidth resources and the CPU resources. When a small window is scaled to a large window, the video quality on the receiver side is affected since the sender will remain the small encoding resolution.